What the E.02 alarm means

The ERC robot controller detected an internal system fault — watchdog, memory, or task scheduling — and halted program execution. In our ESTUN service archive this alarm on ERC / ED3L controller + ESTUN servo systems shows up constantly, and the first on-site inspection almost always locates it.

Most common causes

  • Controller software crash after an unhandled exception
  • Corrupted program or parameter file
  • Power dip during operation
  • Mainboard hardware fault
Field note: The first cause is the most common in the field — check it first, then work through the rest.

Step-by-step field fix

  1. Record the full alarm text and any sub-code on the teach pendant
  2. Power-cycle the controller and note whether E.02 returns immediately
  3. Restore the last known-good project/backup
  4. Check cabinet power quality and the 24 V control supply
  5. Back up all data, then contact support if the fault recurs after restore
Safety first: For ESTUN e-02, the risk on this family is not injury but data: lose the program, parameters and calibration data and weeks of teaching work start over. The self-serviceable action is Record the full alarm text and any sub-code on the teach pendant; anything past that falls under program and calibration data and needs a certified engineer.

How we diagnose system alarms on site

ESTUN e-02 belongs to the system & program family. On ESTUN e-02 the failing stage is ESTUN teaching and programming environment (ESTUN robot controllers (motion-control-platform based)) on the ESTUN robot controllers (motion-control-platform based) - the software layer: corrupted program or parameter files, boot failures, version mismatch, memory and storage media. We start reading ESTUN e-02 at the pendant alarm list (A.xxx / E.xxx segments) and the servo panel display code.

The chain involved in ESTUN e-02 runs: storage media (CF / flash / disk) -> system software and firmware -> parameters and calibration data -> user programs -> runtime.

If ESTUN e-02 comes with slower boots, think media: The CF card, flash or disk inside a controller has a finite life, and heavy log writing shortens it. Ageing media usually announces itself in stages: occasional read/write errors, then slow boots, then a failure to boot at all. The nasty part is that the data may already be damaged. We bring the system up from recovery media first, then salvage user programs and parameters; everything salvaged is stored in two copies, and we set the customer up with a standing backup habit afterwards.

Field notes on this page cover ESTUN e-02 (Controller System Error (ERC)); written by the Henghuan repair team, updated 2026-10-01.

Can't clear it yourself? Contact us for remote diagnosis

Just tell us the alarm code, the robot model and which program was running, and our engineers will help you narrow it down — phone and video remote diagnosis are both free.

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Related System & Program alarms

A.02 — Parameter Setting Error A.10 — Overcurrent A.30 — Regeneration Error / Regenerative Overload A.40 — Main Circuit Overvoltage A.41 — Main Circuit Undervoltage A.51 — Overspeed
Same family: this code belongs to the System & program alarms family - the page collects all System & program-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for INOVANCE · EFORT · JAKA and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the ESTUN e-02 alarm mean?

The ERC robot controller detected an internal system fault — watchdog, memory, or task scheduling — and halted program execution. In our ESTUN service archive this alarm on ERC / ED3L controller + ESTUN servo systems shows up constantly, and the first on-site inspection almost always locates it. ESTUN e-02 sits in the system & program family; on our work orders the highest-frequency trigger for this code is "Controller software crash after an unhandled exception".

QCan I clear a ESTUN e-02 alarm myself?

Whether ESTUN e-02 clears on its own depends on the outcome of "Record the full alarm text and any sub-code on the teach pendant". Finish the flow with "Back up all data, then contact support if the fault recurs after restore" to confirm ESTUN e-02 - do not skip it. If that step is clean, the second most frequent cause on ESTUN e-02 is "Corrupted program or parameter file". After clearing ESTUN e-02, watch it for one shift. A second trip means stop and let an engineer arrive with the right test gear for program and calibration data.

QWhen you handle ESTUN e-02, will my programs and frames get lost?

The commonest causes we see on ESTUN e-02 are "Controller software crash after an unhandled exception, Corrupted program or parameter file, Power dip during operation", so we stock the van against those. For ESTUN e-02 specifically, we carry recovery media and common storage media, but on this family the backup matters more than the spare. For ESTUN e-02, on system alarms the first move is backup; we can walk the customer through preserving data remotely before anything else. Before we roll, tell us what ESTUN e-02 shows on the pendant alarm list (A.xxx / E.xxx segments) and the servo panel display code and what the machine was doing - phone or video triage is free.

The content on ESTUN e-02 was written by Henghuan Robotics service engineers from hands-on repair experience. Alarm descriptions are our own reference summary and may differ by controller or software version — defer to ESTUN documentation, or contact us to confirm. Henghuan is an independent service provider with no affiliation or endorsement by ESTUN.